dnl @synopsis ACX_PTHREAD([ACTION-IF-FOUND[, ACTION-IF-NOT-FOUND]])
dnl
+dnl @summary figure out how to build C programs using POSIX threads
+dnl
dnl This macro figures out how to build C programs using POSIX threads.
dnl It sets the PTHREAD_LIBS output variable to the threads library and
dnl linker flags, and the PTHREAD_CFLAGS output variable to any special
dnl
dnl @category InstalledPackages
dnl @author Steven G. Johnson <stevenj@alum.mit.edu>
-dnl @version 2005-01-14
+dnl @version 2006-05-29
dnl @license GPLWithACException
+dnl
+dnl Checks for GCC shared/pthread inconsistency based on work by
+dnl Marcin Owsiany <marcin@owsiany.pl>
+
AC_DEFUN([ACX_PTHREAD], [
AC_REQUIRE([AC_CANONICAL_HOST])
# which indicates that we try without any flags at all, and "pthread-config"
# which is a program returning the flags for the Pth emulation library.
-acx_pthread_flags="pthreads pthread none -Kthread -kthread lthread -pthread -pthreads -mthreads --thread-safe -mt pthread-config"
+acx_pthread_flags="pthreads none -Kthread -kthread lthread -pthread -pthreads -mthreads pthread --thread-safe -mt pthread-config"
# The ordering *is* (sometimes) important. Some notes on the
# individual items follow:
# -mt: Sun Workshop C (may only link SunOS threads [-lthread], but it
# doesn't hurt to check since this sometimes defines pthreads too;
# also defines -D_REENTRANT)
+# ... -mt is also the pthreads flag for HP/aCC
# pthread: Linux, etcetera
# --thread-safe: KAI C++
# pthread-config: use pthread-config program (for GNU Pth library)
# On Solaris (at least, for some versions), libc contains stubbed
# (non-functional) versions of the pthreads routines, so link-based
- # tests will erroneously succeed. (We need to link with -pthread or
+ # tests will erroneously succeed. (We need to link with -pthreads/-mt/
# -lpthread.) (The stubs are missing pthread_cleanup_push, or rather
# a function called by this macro, so we could check for that, but
# who knows whether they'll stub that too in a future libc.) So,
# we'll just look for -pthreads and -lpthread first:
- acx_pthread_flags="-pthread -pthreads pthread -mt $acx_pthread_flags"
+ acx_pthread_flags="-pthreads pthread -mt -pthread $acx_pthread_flags"
;;
esac
AC_MSG_CHECKING([for joinable pthread attribute])
attr_name=unknown
for attr in PTHREAD_CREATE_JOINABLE PTHREAD_CREATE_UNDETACHED; do
- AC_TRY_LINK([#include <pthread.h>], [int attr=$attr;],
+ AC_TRY_LINK([#include <pthread.h>], [int attr=$attr; return attr;],
[attr_name=$attr; break])
done
AC_MSG_RESULT($attr_name)
LIBS="$save_LIBS"
CFLAGS="$save_CFLAGS"
+ # More AIX lossage: must compile with xlc_r or cc_r
+ if test x"$GCC" != xyes; then
+ AC_CHECK_PROGS(PTHREAD_CC, xlc_r cc_r, ${CC})
+ else
+ PTHREAD_CC=$CC
+ fi
+
+ # The next part tries to detect GCC inconsistency with -shared on some
+ # architectures and systems. The problem is that in certain
+ # configurations, when -shared is specified, GCC "forgets" to
+ # internally use various flags which are still necessary.
+
+ AC_MSG_CHECKING([whether to check for GCC pthread/shared inconsistencies])
+ check_inconsistencies=yes
+ case "${host_cpu}-${host_os}" in
+ *-darwin*) check_inconsistencies=no ;;
+ esac
+ if test x"$GCC" != xyes -o "x$check_inconsistencies" != xyes ; then
+ AC_MSG_RESULT([no])
+ else
+ AC_MSG_RESULT([yes])
+
+ # In order not to create several levels of indentation, we test
+ # the value of "$ok" until we find out the cure or run out of
+ # ideas.
+ ok="no"
+
+ #
+ # Prepare the flags
+ #
+ save_CFLAGS="$CFLAGS"
+ save_LIBS="$LIBS"
+ save_CC="$CC"
+ # Try with the flags determined by the earlier checks.
+ #
+ # -Wl,-z,defs forces link-time symbol resolution, so that the
+ # linking checks with -shared actually have any value
+ #
+ # FIXME: -fPIC is required for -shared on many architectures,
+ # so we specify it here, but the right way would probably be to
+ # properly detect whether it is actually required.
+ CFLAGS="-shared -fPIC -Wl,-z,defs $CFLAGS $PTHREAD_CFLAGS"
+ LIBS="$PTHREAD_LIBS $LIBS"
+ CC="$PTHREAD_CC"
+
+ AC_MSG_CHECKING([whether -pthread is sufficient with -shared])
+ AC_TRY_LINK([#include <pthread.h>],
+ [pthread_t th; pthread_join(th, 0);
+ pthread_attr_init(0); pthread_cleanup_push(0, 0);
+ pthread_create(0,0,0,0); pthread_cleanup_pop(0); ],
+ [ok=yes])
+
+ if test "x$ok" = xyes; then
+ AC_MSG_RESULT([yes])
+ else
+ AC_MSG_RESULT([no])
+ fi
+
+ #
+ # Linux gcc on some architectures such as mips/mipsel forgets
+ # about -lpthread
+ #
+ if test x"$ok" = xno; then
+ AC_MSG_CHECKING([whether -lpthread fixes that])
+ LIBS="-lpthread $PTHREAD_LIBS $save_LIBS"
+ AC_TRY_LINK([#include <pthread.h>],
+ [pthread_t th; pthread_join(th, 0);
+ pthread_attr_init(0); pthread_cleanup_push(0, 0);
+ pthread_create(0,0,0,0); pthread_cleanup_pop(0); ],
+ [ok=yes])
+
+ if test "x$ok" = xyes; then
+ AC_MSG_RESULT([yes])
+ PTHREAD_LIBS="-lpthread $PTHREAD_LIBS"
+ else
+ AC_MSG_RESULT([no])
+ fi
+ fi
+ #
+ # FreeBSD 4.10 gcc forgets to use -lc_r instead of -lc
+ #
+ if test x"$ok" = xno; then
+ AC_MSG_CHECKING([whether -lc_r fixes that])
+ LIBS="-lc_r $PTHREAD_LIBS $save_LIBS"
+ AC_TRY_LINK([#include <pthread.h>],
+ [pthread_t th; pthread_join(th, 0);
+ pthread_attr_init(0); pthread_cleanup_push(0, 0);
+ pthread_create(0,0,0,0); pthread_cleanup_pop(0); ],
+ [ok=yes])
+
+ if test "x$ok" = xyes; then
+ AC_MSG_RESULT([yes])
+ PTHREAD_LIBS="-lc_r $PTHREAD_LIBS"
+ else
+ AC_MSG_RESULT([no])
+ fi
+ fi
+ if test x"$ok" = xno; then
+ # OK, we have run out of ideas
+ AC_MSG_WARN([Impossible to determine how to use pthreads with shared libraries])
+
+ # so it's not safe to assume that we may use pthreads
+ acx_pthread_ok=no
+ fi
- # More AIX lossage: must compile with cc_r
- AC_CHECK_PROG(PTHREAD_CC, cc_r, cc_r, ${CC})
+ CFLAGS="$save_CFLAGS"
+ LIBS="$save_LIBS"
+ CC="$save_CC"
+ fi
else
PTHREAD_CC="$CC"
fi